At least three people have been killed and seven others injured during a shooting at a factory near the Swiss city of Lucern, prosecutors have said.
They said the suspected shooter was among the dead.
Swiss police said in a brief statement that the shooting took place at around 9am local time (08:00 GMT) at a wood processing company called Kronospan in the town of Menznau.
Police said the emergency services were on the scene and the area had been largely cordoned off, but gave no further details, saying only they would give further updates later in the day.
A major police deployment was under way, the statement said.
The local Neue Luzerner Zeitungnewspaper cited a witness as saying that the shooter opened fire in the company canteen.
It was not immediately clear who the shooter was, what the motive might have been or whether the assailant worked for the company.
Owned by Austrian group Kronospan, the factory is the top employer in Menznau, employing around 400 people.
"At the moment we're all in a state of shock," Urs Fluder, a manager at the company, told Radio Pilatus, a local station.
"We will see that the families are properly informed," he added.
Swiss news agency SDA quoted the rescue helicopter service REGA as saying it had flown four seriously injured people to hospital.
Last month, a gunman killed three women and wounded two men in the Swiss village of Daillon, stirring a debate about
Switzerland's fire arms laws that allow its male citizens to retain guns after their mandatory military service.
Switzerland has a longstanding tradition of gun ownership, and ranks third in the world for the number of guns per inhabitant, after the United States and Yemen.